The complete or partial detachment of ligaments, tendons and/or other soft tissues from their associated bones within the body are relatively commonplace injuries, particularly among athletes. Such injuries are generally the result of excessive stresses being placed on these tissues. By way of example, tissue detachment may occur as the result of an accident such as a fall, over-exertion during a work-related activity, during the course of an athletic event, or in any one of many other situations and/or activities. In the case of a partial detachment, the injury will frequently heal itself, if given sufficient time and if care is taken not to expose the injury to further undue stress. In the case of complete detachment, however, surgery may be needed to re-attach the soft tissue to its associated bone or bones.
Numerous devices are currently available to re-attach soft tissue to bone. Examples of such currently-available devices include screws, staples, suture anchors and tacks. In soft tissue re-attachment procedures utilizing screws, the detached soft tissue is typically moved back into its original position over the bone. Then the screw is screwed through the soft tissue and into the bone, with the shank and head of the screw holding the soft tissue to the bone. Similarly, in soft tissue re-attachment procedures utilizing staples, the detached soft tissue is typically moved back into its original position over the bone. Then the staple is driven through the soft tissue and into the bone, with the legs and bridge of the staple holding the soft tissue to the bone. In soft tissue re-attachment procedures utilizing suture anchors, an anchor-receiving hole is generally first drilled in the bone at the desired point of tissue re-attachment. Then a suture anchor is deployed in the hole with a portion of one or more sutures secured to the anchor, with the free end(s) of the suture extending out of the bone. The free ends of the suture are passed through or around the soft tissue and are used to tie the soft tissue securely to the bone.
With any of the above techniques, it is generally desirable to increase the number of fixation points where tissue is secured to bone in order to increase the surface area of the tissue drawn into contact with the bone, which can facilitate healing, and to decrease the load on the tissue at any one point, which can help prevent tissue damage. In the case of soft tissue reattachment with suture anchors, one approach to increasing the number of fixation points is to increase the number of suture anchors. Too many suture anchors, however, can compromise the integrity of the bone due to the amount of bone material that must be impinged and/or removed to install the suture anchors. Another approach to increasing the number of tissue fixation points that does not require an increase in the number of suture anchors is to attach multiple suture strands to each anchor. However, the multiple suture strands extending from an anchor must generally be passed through the same region of tissue because if tissue too remote from the anchor is drawn towards the anchor, the tissue may pucker or fold. Because the multiple suture strands are passed through the same region of tissue, the load on the tissue is not appreciably reduced.
Accordingly, there remains a need for improved methods and devices for attaching tissue to bone.